The Biostatistics Core will continue to serve as a resource and collaborator for all projects and cores related to this program project. The Biostatistics Core personnel are responsible for overseeing data acquisition, for the implementation of all software for data entry and data management tasks, and for training the appropriate personnel. They are also responsible for collaborating with investigators and their staff in monitoring the data acquisition process to identify potential sources of problems and recommend changes. The Biostatistics Core will take a lead in all of the cross-project data analyses outlined in the proposals. Specifically the Biostatistics Core will: 1. Consult on the design of all projects and consult in the application of appropriate statistical and methodological techniques. 2. Collaborate in data analysis and report preparation for all cores and projects. 3. Collaborate in the design of all forms to be used. 4. Continue to support data entry and data management procedures to achieve cost-effective computer use. 5. Facilitate access by all investigators to data collected by the cores. 6. Develop, apply, and implement appropriate statistical data analysis techniques for combining the cross-sectional and longitudinal data that have been gathered.